Golf balls with soft, resilient bimodal ionomeric covers

ABSTRACT

Disclosed are golf balls having soft, resilient bimodal ionomeric covers with improved softness and scuff resistance and methods for their preparation. The soft, resilient bimodal ionomeric covers comprise at least partially neutralized mixtures of carboxylate functionalized terpolymers (molecular weight between about 80,000 and 500,000) with carboxylate functionalized ethylene low copolymers (molecular weight between about 2,000 and 30,000).

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation application of U.S. application Ser.No. 12/315,731, filed on Dec. 5, 2008, now allowed, which in turn is acontinuation-in-part application of U.S. application Ser. No.11/893,831, filed on Aug. 17, 2007, now issued as U.S. Pat. No.7,488,778, which in turn is a continuation application of U.S.application Ser. No. 11/101,078, filed on Apr. 6, 2005, now issued asU.S. Pat. No. 7,273,903, which in turn is a continuation application ofU.S. application Ser. No. 10/854,725, filed on May 26, 2004, now issuedas U.S. Pat. No. 7,037,967, which in turn is a divisional application ofU.S. application Ser. No. 10/376,969, filed on Feb. 28, 2003, now issuedas U.S. Pat. No. 6,762,246, which in turn is a divisional application ofU.S. application Ser. No. 09/924,194, filed on Aug. 8, 2001, now issuedas U.S. Pat. No. 6,562,906, which in turn claims priority under 35U.S.C. §119(e) to U.S. Provisional Appln. No. 60/224,668, filed on Aug.11, 2000, and to U.S. Provisional Appln. No. 60/279,023, filed on Mar.27, 2001. Each of the above identified applications is incorporatedherein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to golf balls having covers comprising abimodal ionomeric composition. The bimodal ionomeric cover compositioncomprises mixtures of carboxylate functionalized terpolymers that are atleast partially neutralized.

2. Description of the Related Art

Ionomeric resins (ionomers) are useful materials for the construction ofgolf balls, among other things. Ionomers are ionic copolymers that areobtained after copolymerization of an olefin such as ethylene with anunsaturated carboxylic acid, such as acrylic acid (AA), methacrylic acid(MAA), or maleic acid, and optionally softening monomers. Neutralizingagents—which for the purposes of this application are ionic compoundscontaining metal cations such as sodium or zinc ions—are used toneutralize at least some portion of the acidic groups in the copolymerresulting in a thermoplastic resin exhibiting enhanced properties. Forexample, golf balls constructed using ionomeric materials have improvedresilience and durability as compared with balata ball construction. Asa result of their resilience, toughness, durability and flightcharacteristics, various ionomeric resins sold by E. I. DuPont deNemours & Company under the trademark “Surlyn®” and by the ExxonCorporation under the trademark “Escor®” and the tradename “lotek” havebecome materials of choice for the construction of golf balls over thetraditional balata (trans polyisoprene, natural or synthetic) rubbers.The softer balata covers, although exhibiting enhanced playabilityproperties, lack the durability necessary for repetitive play. However,the advantages gained in increased durability of the ionomeric covershave been offset to some degree by their decreased playability. This isbecause the durable ionomeric resins tend to be very hard when used forgolf ball cover construction, and thus lack the degree of softnessrequired to impart the spin necessary to control the ball in play.

Current commercial ionomers derived from dipolymers have not been ableto produce a satisfactory combination of the desirable properties of the“hard” ionomeric resins, for example, good impact resistance andcarrying distance, and the desirable properties of soft balata covers,for example, playability (that is, “spin”). These are properties desiredby the more skilled golfer.

Terpolymers made from copolymerization of (a) an olefin, such asethylene (b) an unsaturated carboxylic acid and (c) other comonomers,such as alkyl acrylates and/or alkyl methacrylates, provide “softer”resins which can be neutralized to form softer ionomers. However, thesesofter ionomeric resins by themselves are not suitable for golf ballcovers because they have reduced resilience and heat stability.

In various attempts to produce a durable, high spin ionomeric golf ball,the golfing industry has blended the hard ionomeric resins with a numberof the softer ionomeric resins. U.S. Pat. Nos. 4,884,814 and 5,120,791are directed to cover compositions containing blends of hard and softionomeric resins. The hard copolymers typically are made from an olefinand an unsaturated carboxylic acid. It has been found that golf ballsformed from hard-soft ionomer blends tend to become scuffed more readilythan covers made of hard ionomer alone. U.S. Pat No. 5,902,855 isdirected to golf balls with scuff resistant covers comprising blends ofionomers with Shore D hardness of about 40-64.

The golfing industry has also developed golf ball covers formed frompolyurethane compositions. These covers combine good scuff resistanceand a softness that enables spin control and good playability. Becauseof this combination of desirable factors, golf balls with polyurethanecovers are considered to be “premium” balls for the more skilled player.However, polyurethane covers are low in resilience and hence detractfrom the performance of the golf ball. In addition, thermosetpolyurethane covers are more difficult to process than thermoplasticionomer resins and the material costs are also higher, makingpolyurethane balls more expensive to manufacture.

Thus, it would be useful to develop a golf ball cover material having acombination of softness, resilience and good scuff resistance withimproved heat stability, melt processibility and lower cost. It is alsodesirable to develop a golf ball having a favorable combination ofplayability and durability.

SUMMARY OF THE INVENTION

In one aspect, the present invention is a golf ball having a cover,wherein the cover has a scuff resistance no greater than about 3.0 outof 5 and wherein the cover comprises or consists essentially of athermoplastic composition that includes:

-   -   (a) at least one E/X/Y copolymer having a weight average        molecular weight of from about 80,000 to about 500,000 obtained        by the copolymerization of comonomers E, X, and Y wherein E is        ethylene, X is a C₃ to C₈ α,β-ethylenically unsaturated        carboxylic acid, and Y is an alkyl acrylate or an alkyl        methacrylate softening comonomer wherein the alkyl groups have        from 1 to 8 carbon atoms, wherein X is present in an amount of        from about 2 to about 30 wt. % of the E/X/Y copolymer, and Y is        present in an amount of from about 17 to about 40 wt. % of the        E/X/Y copolymer; and    -   (b) one or more E/acrylic acid and/or E/methacrylic acid        copolymers having a weight average molecular weight of from        about 2,000 to about 30,000 and having from about 3 to about 20        wt. % acrylic acid and/or methacrylic acid present based on the        weight of (b), the copolymer present in the composition in an        amount of from about 5 to about 30 wt. % based on the combined        weight of (a)+(b);        and wherein: (1) the thermoplastic composition is at least        partially neutralized by at least one neutralizing agent having        one or more alkali metal, transition metal, or alkaline earth        metal cations; and (2) the composition has a Shore D hardness of        less than or equal to about 50 and a flex modulus less than or        equal to about 20 kpsi.

In another aspect, the present invention is a golf ball having a covercomprising or consisting essentially of said thermoplastic compositionand further comprising at least one additional component selected fromcopolymers in the group consisting of nonionomeric thermoplasticcopolymers and dipolymeric ionomeric thermoplastic copolymers, saidcopolymers having a weight average molecular weight of from about 80,000to about 500,000.

In another aspect, the present invention is a process for making a golfball having a cover that is scuff resistant, the process comprising thesteps: forming a cover over a golf ball core, wherein the cover has ascuff resistance of not greater than about 3.0 out of 5 and comprises orconsists essentially of a thermoplastic composition that includes:

-   -   (a) at least one E/X/Y copolymer having a weight average        molecular weight of from about 80,000 to about 500,000 obtained        by the copolymerization of comonomers E, X, and Y wherein E is        ethylene, X is a C₃ to C₈ α,β-ethylenically unsaturated        carboxylic acid, and Y is an alkyl acrylate or an alkyl        methacrylate softening comonomer wherein the alkyl groups have        from 1 to 8 carbon atoms, wherein E is present in an amount of        from about 30 wt % to about 81 wt % based on the weight of the        copolymer, X is present in an amount of from about 2 to about 30        wt. % of the copolymer, Y is present in an amount of from about        17 to about 40 wt. % of the copolymer;    -   (b) one or more E/acrylic acid and/or E/methacrylic acid        copolymers having a weight average molecular weight of from        about 2,000 to about 30,000 and having from about 3 to about 20        wt. % acrylic acid and/or methacrylic acid present based on the        weight of (b), the copolymer present in the composition in an        amount of from about 5 to about 30 wt. % based on the combined        weight of (a)+(b);        and wherein: (1) the thermoplastic composition is at least        partially neutralized by one or more alkali metal, transition        metal, or alkaline earth metal cations and (2) the composition        has a Shore D hardness of less than or equal to about 50 and a        flex modulus of less than or equal to about 20 kpsi.

In still another aspect, the present invention is a one-piece golf ballhaving a scuff resistance not greater than about 3.0 out of 5 andcomprises or consists essentially of a thermoplastic composition thatincludes:

-   -   (a) at least one E/X/Y copolymer having a weight average        molecular weight of from about 80,000 to about 500,000 obtained        by the copolymerization of comonomers E, X, and Y wherein E is        ethylene, X is a C₃ to C₈ α,β-ethylenically unsaturated        carboxylic acid, and Y is an alkyl acrylate or an alkyl        methacrylate softening comonomer wherein the alkyl groups have        from 1 to 8 carbon atoms, wherein E is present in an amount of        from about 30 wt % to about 81 wt % based on the weight of the        copolymer, X is present in an amount of from about 2 to about 30        wt. % of the copolymer, Y is present in an amount of from about        17 to about 40 wt. % of the copolymer;    -   (b) one or more E/acrylic acid and/or E/methacrylic acid        copolymers having a weight average molecular weight of from        about 2,000 to about 30,000 and having from about 3 to about 20        wt. % acrylic acid and/or methacrylic acid present based on the        weight of (b), the copolymer present in the composition in an        amount of from about 5 to about 30 wt. % based on the combined        weight of (a)+(b);        and wherein: (1) the thermoplastic composition is at least        partially neutralized by one or more alkali metal, transition        metal, or alkaline earth metal cations and (2) the composition        has a Shore D hardness of less than or equal to about 60 and a        flex modulus of less than or equal to about 40 kpsi.

In still another aspect, the present invention is a one-piece golf ballas described hereinabove, further comprising at least one additionalcopolymer component selected from copolymers in the group consisting ofnonionomeric thermoplastic copolymers and dipolymeric ionomericthermoplastic copolymers, said copolymers having a weight averagemolecular weight of from about 80,000 to about 500,000.

In another aspect, the present invention is a process for producing aone-piece golf ball as described herein, comprising the step: molding acomposition of the present invention into the shape of a golf ball.

BRIEF DESCRIPTION OF FIGURES

FIG. 1 is a plot of Atti (PGA) compression versus COR (125 ft/secinitial velocity) showing the properties of molded spheres of highterpolymer ionomer resins useful in the present invention as comparedwith other conventional ionomer resins.

DETAILED DESCRIPTION OF THE INVENTION

All references disclosed herein are incorporated by reference.

“Copolymer” means polymers containing two or more different monomers.The terms “dipolymer” and “terpolymer” mean polymers containing only twoand three different monomers respectively. The phrase “copolymer ofvarious monomers” means a copolymer whose units are derived from thevarious monomers.

“Bimodal ionomers” means ionomers with high terpolymer components andlow copolymer components wherein the Mw of the high terpolymer and theMw of the low copolymer are sufficiently different that two distinctmolecular weight peaks can be observed when measuring Mw of the blend bygel permeation chromatography (GPC) with a high-resolution column.

“Ethylene/(meth)acrylic acid (also abbreviated as E/(M)AA)” means“ethylene/acrylic acid copolymers and/or ethylene/methacrylic acidcopolymers.”

According to the present invention the soft, resilient thermoplasticcompositions described herein provide an improved balance of propertiesand processibility. The thermoplastic compositions are “bimodal”ionomers that are at least partially neutralized and are derived fromblends of high molecular weight terpolymers (high terpolymers) and lowmolecular weight copolymers (low copolymers). That is to say, they aremelt-blends of: (1) terpolymers having a weight average molecular weight(Mw) of about 80,000 to about 500,000 obtained by the copolymerizationof (a) ethylene, (b) α,β-ethylenically unsaturated C₃₋₈ carboxylic acidsand (c) softening comonomers selected from alkyl acrylate and alkylmethacrylate with a weight average molecular weight (Mw) of about 80,000to about 500,000; and (2) low copolymers having a Mw of from about 2,000to about 30,000, obtained by copolymerization of ethylene withα,β-ethylenically unsaturated C₃₋₈ carboxylic acids and are at leastpartially neutralized according to methods well known in the art by oneor more alkali metal, transition metal, or alkaline earth metal cations.Particularly preferred low copolymers are copolymers of E/(M)AA, andmost preferred low copolymers are the low dipolymers.

The high terpolymers can be blends of high terpolymers and the lowcopolymers can be blends of low copolymers. The ionomers derived fromhigh terpolymers can also be referred to as soft resilient ionomers(SRI), and are characterized by an Atti Compression and a Coefficient ofRestitution (COR) that each independently falls within the area that isdefined by the vertices A₁, A₂, and N [hereinafter designated A₁-A₂-N]of FIG. 1.

It has been found that, by proper selection of the low copolymer thethermoplastic compositions of this invention have demonstrated bothenhanced melt processibility, enhanced resilience, enhanced heatstability and enhanced scuff resistance. This combination of theproperty enhancements is contrasted to the reduction in heat stabilitythat would be expected with higher melt flows. These unique soft,resilient bimodal ionomer compositions are highly useful for injectionmolding applications, including production of golf ball covers and golfballs comprising such covers.

According to this invention, the weight percent (wt. %) of the highterpolymer is from about 70 to about 97 wt. %, preferably from about 80to about 95 wt. %, and the weight percent of the low copolymer is fromabout 3 to about 30%, preferably from about 5 to about 20 wt. %. Weightpercentage is based on the total combined weight of the high terpolymerand the low copolymer. Preferably at least 30%, and more preferably atleast 45%, of the acid moieties are neutralized by neutralizing agentshaving cations of at least one alkali metal, alkaline earth metal, ortransition metal. A composition of this mixture has a Shore D hardnessof less than or equal to 50, preferably from about 10 to about 45, andmore preferably from about 15 to about 40, and a flex modulus of lessthan or equal to 20 kpsi.

The soft, resilient bimodal ionomer compositions described above, orblends thereof with nonionomeric thermoplastic copolymers and/or withdipolymeric ionomeric thermoplastic copolymers having a M_(w) of about80,000 to about 500,000, can be processed in molding applications forgolf ball applications such as the cover of 2-, 3- or multiple-piecegolf balls, and as thermoplastic 1-piece balls.

In accordance with this invention, the Mw of the high terpolymers isseparated from the Mw of the low copolymers sufficiently that the peaksfor the high copolymers are distinctly separated from the peaks for thelow copolymers when the blend molecular weight distribution isdetermined by GPC with a high-resolution column. Preferably, to obtainsufficient molecular weight separation in the blends of the presentinvention, high terpolymers having Mw's that are lower in the highterpolymer molecular weight range are blended with low copolymers havingMw's that are lower in the low copolymer molecular weight range (forexample, high terpolymers having a Mw of about 80,000 with lowcopolymers having a Mw of about 2,000). This becomes less important asthe Mw's of the high terpolymers increase.

Preferably the low copolymers are present in the range of from about 5to about 30 weight percent based on the combined weight of the highcopolymers and the low copolymers in the blend.

Preferably the high terpolymers and low copolymers are at leastpartially neutralized by at least one of the alkali metal, alkalineearth metal or transition metal cations. Preferably at least 30%, morepreferably at least 45%, even more preferably at least 50%, and mostpreferably at least 60% of the total number of acid moieties in the highcopolymers and low copolymers are neutralized. Cations are selected fromthe group consisting of lithium*, sodium*, potassium, magnesium*,calcium, barium, lead, tin, or zinc* (* indicates a preferred cation),or a combination of such cations. More preferred cations are lithium,magnesium and zinc, with zinc especially preferred.

Neutralization can be effected by first making the high terpolymerand/or the low dipolymer and treating the polymer(s) with inorganicbase(s) with alkali metal, alkaline earth metal or transition metalcation(s). Methods for preparing ionomers from copolymers are well knownin the art. The resulting ionomer(s) can be melt-blended with otherionomers or polymers. To achieve desired higher neutralization theresulting blend of ionomers can be further neutralized. Preferably thehigh terpolymers and low copolymers are melt-blended and thenneutralized in situ so that the desired level of neutralization can beachieved in one step.

Optionally, the composition can include up to 100 parts by weight oforganic acid salts, up to 200 parts by weight thermoplastic elastomers,up to 170 parts by weight fillers and up to 50 parts of additional highmolecular weight dipolymer (e.g. nonionomeric thermoplastic copolymersand/or dipolymeric ionomeric thermoplastic copolymers having a M_(w) offrom about 80,000 to about 500,000) based on 100 parts by weight of theof the soft, resilient bimodal ionomer of the high terpolymer/lowcopolymer blend. Other additives such as stabilizers and processing aidscan be included.

The components of the blends useful in this invention are more fullydescribed below.

High Terpolymers

The high terpolymers useful in this invention are preferably ‘direct’acid copolymers (as opposed to grafted copolymers) having an Mw of fromabout 80,000 to about 500,000. Preferably they have polydispersities(Mw/Mn) of about 1 to about 15.

Terpolymers of the present invention are preferably obtained bycopolymerization of (a) an alpha olefin (b) a C₃₋₈ α,β-ethylenicallyunsaturated carboxylic acid and (c) a softening monomer. By “softening”,it is meant that the polymer is made less crystalline. Suitable“softening” comonomers are monomers selected from alkyl acrylate andalkyl methacrylate, wherein the alkyl groups have from 1 to 12 carbonatoms, and vinyl acetate.

The ethylene acid copolymers can be described as E/X/Y copolymers whereE is ethylene, X is the α,β-ethylenically unsaturated carboxylic acid,and Y is a softening comonomer. X is present in an amount ranging fromabout 2 to about 20 (preferably from about 5 to about 15, and mostpreferably from about 5 to about 13) wt. % of the polymer, and Y ispresent in an amount which ranges from about 17 to about 40 wt. % of theE/X/Y copolymer (preferably from about 20 to about 35) wt. % of thepolymer. The high terpolymers useful in this invention have an Atti(PGA) Compression and a COR that each, independently, fall within areaA₁-A₂-N, B₁-B₂—N, C₁-C₂—N, D₁-D₂-N, or even area E₁-E₂-N of FIG. 1.Preferably, the Atti Compression and Coefficient of Restitution eachindependently fall within area B₁-B₂—N of FIG. 1, more preferably withinarea C₁-C₂—N of FIG. 1 and even more preferably within area D₁-D₂-N ofFIG. 1. Most preferably, the Atti Compression and Coefficient ofRestitution each independently fall within E₁-E₂-N of FIG. 1. AttiCompressions and Coefficients of Restitution that fall on the notedlines are considered to be within a specified area for purposed of thepresent invention. By way of non-limiting explanation as to what isintended by Atti Compression and a Coefficient of Restitution that eachindependently fall within the area A₁-A₂-N, reference is made to FIG. 1.It would be within the scope of this invention to use a terpolymer withan Atti Compression of 40 and a COR of 0.700 for the neat resin spheres,as well as a terpolymer having an Atti Compression of 40 and a COR of0.650. It would also be within the scope of this invention to use aterpolymer with an Atti compression of 2 and a COR of 0.564 for the neatresin spheres.

The ethylene acid copolymers with high levels of acid (X) are difficultto prepare in continuous polymerizers because of monomer-polymer phaseseparation. This difficulty can be avoided however by use of “co-solventtechnology” as described in U.S. Pat. No. 5,028,674 which isincorporated herein by reference or by employing somewhat higherpressures than those at which copolymers with lower acid can beprepared.

Of particular note are high terpolymers comprising ethylene, 6.2 wt. %of acrylic acid and 28 wt. % of n-butylacrylate with a melt index of 200[hereinafter, specific blends can be referred to using a generic formatE/wt % X/wt % Y, wherein the wt % of component X and the wt % ofcomponent Y are indicated. A specific measured property, for example themelt index (MI), can be specified in the generic formula as well. Forexample, the blend above can be described as E/6.2AA/28nBA(200 MI)].These terpolymers may be prepared by using “co-solvent technology” asdescribed in U.S. Pat. No. 5,028,674. These terpolymers can be convertedto ionomers suitable for use herein. FIG. 1 shows a plot of Atticompression (see below) versus Coefficient of Restitution at 125 ft/secinitial velocity (COR-125) of molded, neat resin spheres showing theproperties of spheres of these high terpolymer resins compared tospheres of other resins. By inspection of FIG. 1, it can be observedthat these copolymers have Atti Compression and a Coefficient ofRestitution values that each independently fall within the area A₁-A₂-Nin FIG. 1.

Low Copolymers

The low copolymers useful in this invention are preferably ‘direct’ acidcopolymers having an Mw of from about 2,000 to about 30,000. Preferablythey have polydispersities (Mw/Mn) of about 1 to about 10. They arecopolymers that are preferably obtained from copolymerization of analpha olefin, preferably ethylene and a C₃₋₈ α,β-ethylenicallyunsaturated carboxylic acid, preferably acrylic and/or methacrylic acid.Preferably the acid moiety in these copolymers is present in a range offrom about 3 to about 20 (preferably from about 3 to about 15, and mostpreferably from about 5 to about 10) wt. % of the polymer.

Often these low copolymers are referred to as acid copolymer waxes andare commercially available from Honeywell (examples are indicated inTable 1 with their molecular weights).

TABLE 1 Mn Mw Polydispersity Composition/MI (10³) (10³) (Mw/Mn) AC540E/5AA/575 cps 4.3 7.5 1.7 Brookfield @140 C. ** AC580 E/10AA/650 cps 4.826.0 5.4 Brookfield @140 C. ** AC5120 E/15AA/650 cps 3.0 5.2 1.7Brookfield @140 C. ** ** No MI data available; Brookfield data definedby Honeywell or formerly Allied Signal

Of particular note is the copolymer composed of ethylene and 5% acrylicacid [E/5AA] commercially available from Honeywell as AC540.

Ionomers

Ionomers of the high terpolymers and of the low copolymers when madeseparately can be made by methods well known in the art. For example,U.S. Pat. No. 3,264,272 describes a process for making ionomers suitablefor use in the practice of the present invention. The degree ofneutralization and the acid level should be selected so that theresulting ionomers of the high terpolymers and the ionomers of the lowcopolymers remain melt-processible and meet the indicated performancestandards.

The soft, resilient bimodal ionomers of high terpolymer/low copolymerblends can be made by melt blending the melt processible ionomersseparately made and then optionally further neutralizing with the sameor different cations to achieve desired levels of neutralization of theresulting blend of ionomers. Preferably the non-neutralized highterpolymers and low copolymers are melt-blended and then neutralized insitu. In this case the desired level of neutralization can be achievedin one step.

Preferably the acid moieties in the resulting bi-modal ionomer of thehigh copolymers and low copolymers are at least partially neutralized toa level of at least 30%, alternatively at least 45%, alternatively atleast 50%, alternatively at least 60%.

Thermoplastic Resins

As indicated above, the soft, resilient bimodal compositions describedabove may also be blended with additional nonionomeric thermoplasticcopolymers and/or dipolymeric ionomeric thermoplastic copolymers with aweight average molecular weight of from about 80,000 to about 500,000.The additional thermoplastic polymer components can be selected fromamong copolyetheresters, copolyetheramides, elastomeric polyolefins,styrene diene block copolymers and thermoplastic polyurethanes, theseclasses of polymers being well known in the art.

The nonionic thermoplastic resins include, by way of non-limitingillustrative examples, thermoplastic elastomers, such as polyurethane,poly-ether-ester, poly-amide-ether, polyether-urea, PEBAX (a family ofblock copolymers based on polyether-block-amide, commercially suppliedby Atochem), styrene-butadiene-styrene (SBS) block copolymers,styrene(ethylene-butylene)-styrene block copolymers, etc., polyamide(oligomeric and polymeric), polyesters, polyolefins including PE, PP,E/P copolymers, etc., ethylene copolymers with various comonomers, suchas vinyl acetate, (meth)acrylates, (meth)acrylic acid,epoxy-functionalized monomer, CO, etc., functionalized polymers withmaleic anhydride, epoxidization etc., either by copolymerization or bygrafting, elastomers such as EPDM, metallocene catalyzed PE andcopolymer, ground up powders of the thermoset elastomers, etc.

Ionomeric copolymers can be blended with the soft, resilient bimodalresin, using well-known techniques, to produce products having desirableproperties, including lower hardness and higher resilience as comparedwith blends of conventional ionomers. Non-limiting, illustrativeexamples of suitable ionomers include E/15MAA/Na, E/19MAA/Na, E/15AA/Na,E/19AA/Na, E/15MAA/Mg and E/19MAA/Li, wherein the metal cation used isindicated at the end of the abbreviated copolymer composition name.These ionomeric blends are considered to be within the scope of thepresent invention to the extent that they exhibit the definedperformance characteristics of this invention.

The copolyetheresters are discussed in detail in patents such as U.S.Pat. Nos. 3,651,014; 3,766,146; and 3,763,109. Preferredcopolyetherester polymers are those where the polyether segment isobtained by polymerization of tetrahydrofuran and the polyester segmentis obtained by polymerization of tetramethylene glycol and phthalicacid. The more polyether units incorporated into the copolyetherester,the softer the polymer.

The copolyetheramides are also well known in the art as described inU.S. Pat. No. 4,331,786, for example. They are comprised of a linear andregular chain of rigid polyamide segments and flexible polyethersegments.

The elastomeric polyolefins are polymers composed of ethylene and higherprimary olefins such as propylene, hexene, octene and optionally1,4-hexadiene and or ethylidene norbornene or norbornadiene. Theelastomeric polyolefins can be functionalized with maleic anhydride.

Thermoplastic polyurethanes are linear or slightly chain-branchedpolymers consisting of hard blocks and soft elastomeric blocks. They areproduced by reacting soft hydroxy-terminated elastomeric polyethers orpolyesters with diisocyanates such as methylene diisocyanate (MDI) ortoluene diisocyanate (TDI). These polymers can be chain extended withglycols, diamines, diacids, or aminoalcohols. The reaction products ofthe isocyanates and the alcohols are called urethanes and these blocksare relatively hard and high-melting. These hard, high-melting blocksare responsible for the thermoplastic nature of the polyurethanes.

Block styrene diene copolymers are composed of polystyrene units andpolydiene units. The polydiene units are derived from polybutadiene,polyisoprene units or copolymers of these two. In the case of thecopolymer it is possible to hydrogenate the polyolefin to give saturatedrubbery backbone segments. These materials are usually referred to asSBS, SIS or SEBS thermoplastic elastomers and they can also befunctionalized with maleic anhydride.

Other polymers that can be blended with the “soft, resilient bimodal”composition described above include LDPE, LLDPE, mPE, EPDM, E/Pcopolymers, Ethylene copolymers containing at least one of the groupconsisting of VA, nBA, CO, GMA, MA, EA, and the MAN grafted copolymers.

Fillers

An optional filler component of the subject invention is chosen toimpart additional density to the soft, resilient bimodal ionomers orblends thereof with other materials. Preferred densities for golf ballsinclude densities in the range starting with the density of unfilledpolymer to 1.8 gm/cc. Generally, the filler will be inorganic, having adensity greater than about 4 gm/cc, preferably greater than 5 gm/cc, andwill be present in amounts between 0 and about 60 wt. % based on thetotal weight of the composition. Examples of useful fillers include zincoxide, barium sulfate, lead silicate and tungsten carbide, tin oxide, aswell as the other well known corresponding salts and oxides thereof. Itis preferred that the filler materials be non-reactive or almostnon-reactive with the polymer components described above when theionomers are less than completely neutralized. If the ionomers are fullyneutralized, reactive fillers may be used. Zinc Oxide grades, such asZinc Oxide, grade XX503R available from Zinc Corporation of America,that do not react with any free acid to cause cross-linking and a dropin MI are preferred, particularly when the ionomer is not fullyneutralized.

Other Components

Other optional additives include titanium dioxide, which is used as awhitening agent or filler; other pigments, optical brighteners;surfactants; processing aids; etc.

Uses of the Soft, Resilient Bimodal Ionomer Composition in Golf Balls

The soft, resilient bimodal ionomers described herein are usefulsubstitutions for one or more materials taught in the art at the levelstaught in the art for use in covers of golf balls, or one-piece golfballs. See, for example, U.S. Pat. Nos. 4,274,637; 4,264,075; 4,323,247;4,337,947, 4,398,000; 4,526,375; 4,567,219; 4,674,751; 4,884,814;4,911,451; 4,984,804; 4,986,545; 5,000,459; 5,068,151; 5,098,105;5,120,791; 5,155,157; 5,197,740; 5,222,739; 5,253,871; 5,298,571;5,321,089; 5,328,959; 5,330,837; 5,338,038; 5,338,610; 5,359,000;5,368,304; 5,567,772; 5,757,483; 5,810,678; 5,873,796; 5,902,855;5,971,870; 5,971,871; 5,971,872; 5,973,046; 5,976,443; 6,018,003;6,096,830; and PCT Patent Application Publication WO 99/48569.

Golf balls prepared in accordance with this invention comprise a covermade from the soft, resilient bimodal ionomer described herein replacingany traditional golf ball cover material such as Surlyn® ionomer resin,balata rubber or thermoset /thermoplastic polyurethanes and the like.Said golf balls will have a traditional dimple pattern and may be coatedwith a polyurethane coating or be painted for appearance purposes, butsuch a coating and/or painting will not affect the performancecharacteristics of the ball. However, coating and/or painting may affectthe scuff resistance of the ball. In particular, such coating and/orpainting may improve scuff resistance over that of an unfinished ball.For the purposes of this invention, any coating and/or painting are notconsidered to be part of a golf ball cover.

Two-Piece Golf Ball

As used herein, the term “two-piece ball” refers to a golf ballcomprising a core and a cover. These two-piece balls are manufactured byfirst molding the core from a thermoset or thermoplastic composition,positioning these preformed cores in injection molding cavities usingretractable pins, then injection molding the cover material around thecores. Alternatively, covers can be produced by compression moldingcover material over the cores. The soft, resilient bimodal ionomerdescribed herein can be used as the cover of such golf balls to preparea golf ball of this invention.

Three-Piece Golf Ball

As used herein, the term “three-piece ball” refers to a golf ballcomprising a center, a traditional elastomeric winding wound around thecenter, and a cover. Three-piece golf balls are manufactured by wellknown techniques as described in, for example, U.S. Pat. No. 4,846,910.The soft, resilient bimodal ionomer described herein can be used as thecover of such golf balls to prepare a golf ball of this invention.

Multi-Layer Golf Ball

As used herein, the term “multi-layer ball” refers to a golf ballcomprising a core, a cover, and one or more mantles between the core andthe cover. These multi-layer balls are manufactured by first molding ormaking the core, typically compression or injection molding themantle(s) over the core and then compression or injection molding acover over the mantle. The soft, resilient bimodal ionomer describedherein can be used as the cover of such golf balls to prepare a golfball of this invention.

As indicated above, golf ball cores may be solid or wound. Solid coresmay be molded in one piece using compression or injection moldingtechniques. A wound core is generally produced by winding a very largeelastic thread around a solid or liquid-filled balloon center. Asindicated, additional mantle layers may be applied over the core toproduce a multi-layer ball. Since the core material is not an integralpart of the present invention, a detailed description of specific typesof core materials that may be used with the cover compositions of thepresent invention are not specifically set forth herein. For thepurposes of this invention, the term core includes solid or wound coresand also includes any mantle layers present in multi-layer balls.

One-Piece Golf Ball

As used herein, the term “one-piece ball” refers to a golf ball moldedin toto from a thermoplastic composition, i.e., not having elastomericwindings, cores or mantles and in which the “cover” is a homogeneoussolid spheroid. The one-piece molded ball will have a traditional dimplepattern and may be coated with a urethane lacquer or be painted forappearance purposes, but such a coating and/or painting will not affectthe performance characteristics of the ball. These one-piece balls aremanufactured by direct injection molding techniques or by compressionmolding techniques. The soft, resilient bimodal ionomer described hereinis used in such balls in combination with other materials typically usedin these balls to prepare a golf ball of this invention.

Covers for golf balls comprising the soft, resilient bimodal ionomerdescribed herein, or blends thereof with other ionomers or non-ionomericthermoplastic resins, are included in this invention. The covers can bemade by injection or compression molding the soft, resilient bimodalionomer described above (with or without organic acid or filler, othercomponents, and other thermoplastics including other ionomers) over athermoplastic or thermoset core of a two-piece golf ball, over windingsaround a thermoplastic or thermoset center, or over the intermediatemantle layers of a multi-layer golf ball.

The specific combinations of resilience and compression used in thepractice of the subject invention will in large part be dependent uponthe type of golf ball desired (e.g., one-piece, two-piece, three-piece,or multi-layered), and in the type of performance desired for theresulting golf ball as detailed below. In addition, a golf ball mustmeet the mass limit (45 grams) set by the United States GolfingAssociation (U.S.G.A.). Preferably, the ball has a density of about 1.14gm/cc. In two-piece, three-piece or multi-layer balls, fillers asdescribed above may be added to the cores, mantles and/or covers asrequired to provide golf balls meeting the mass limit. Depending on thecomposition(s) of the other pieces of the ball, covers of this inventioncan be prepared from the soft, resilient bimodal ionomer compositionsdescribed herein modified with filler(s) as described above to meet themass limit.

Of note are one-piece balls in which the soft, resilient bimodal ionomeris modified with fillers as described above to provide a golf ballmeeting the mass limit (45 grams) set by the U.S.G.A. Preferably, enoughfiller is used so that the ball has a density 1.14 gm/cc. The presentinvention includes one-piece balls comprising a composition having aShore D hardness less than or equal to 60 and a flex modulus less thanor equal to 40 kpsi. Preferred are one-piece balls comprising acomposition having a Shore D hardness of from about 10 to about 55; morepreferred are one-piece balls comprising a composition having a Shore Dhardness of from about 15 to about 50.

The golf balls of the present invention can be produced by moldingprocesses that include but are not limited to those which are currentlywell known in the golf ball art. For example, the golf balls can beproduced by injection molding or compression molding the novel covercompositions described herein around a wound or solid molded core toproduce a golf ball having a diameter of about 1.680-1.800 inches andtypically but not necessarily having a mass of about 45 g.

As indicated, the golf balls of this invention can be produced byforming covers comprising the soft, resilient bimodal ionomercompositions around cores by molding processes. For example, incompression molding, the cover composition is formed via injection at,for example, about 380° F. to about 450° F. into smooth hemisphericalshells which are positioned around the core in a dimpled golf ball moldand subjected to compression molding at, for example, 200-300° F. forabout 2 to about 10 minutes, followed by cooling at 50-70° F. for about2 to about 10 minutes, to fuse the shells together to form a unitaryball. In one type of injection molding, the cover composition isinjected directly around the core placed in the center of a golf ballmold for a period of time at a mold temperature from about 50° F. toabout 100° F.

One-piece balls may be prepared by similar injection molding methods,except that a core is not present in the golf ball mold during themolding process.

After molding, the golf balls produced may undergo various furtherprocessing steps such as buffing, painting and marking.

Without further elaboration, it is believed that one skilled in the artusing the preceding description can utilize the present invention to itsfullest extent. The following Examples are, therefore, to be construedas merely illustrative, and not limiting of the disclosure in any waywhatsoever.

EXAMPLES AND COMPARATIVE EXAMPLES Examples 1-13 and Comparative Examples14-15

A master blend of 90 parts by weight of E/6.2AA/28nBA (200 MI) highterpolymer and 10 parts by weight of E/5AA (AC540) low copolymer wasprepared using standard blending techniques.

Portions of the master blend were neutralized on a single screw extruderwith a series of neutralizing agents at various loadings, i.e. ZnOconcentrate for Example 1 through 3, LiOH concentrate for Example 4through 7, Na₂CO₃ concentrate for Example 8 through 10, and Mg(OH)₂concentrate for Example 1 through 13 to produce soft and resilientbimodal ionomers. The cation contents were determined by elementalanalysis and the melt indices were determined by standard techniques andare reported in Table 2.

TABLE 2 Ion type MI Ex. Composition Master Blend (wt %) (ESL) 1 90%E/6.2AA/28nBA200MI:10% E/5AA Zn (2.08%) 0.42 2 90%E/6.2AA/28nBA200MI:10% E/5AA Zn (1.67%) 1.1 3 90% E/6.2AA/28nBA200MI:10%E/5AA Zn (1.36%) 2.2 4 90% E/6.2AA/28nBA200MI:10% E/5AA Li (0.48%) 1.9 590% E/6.2AA/28nBA200MI:10% E/5AA Li (0.47%) 3.0 6 90%E/6.2AA/28nBA200MI:10% E/5AA Li (0.47%) 3.6 7 90% E/6.2AA/28nBA200MI:10%E/5AA Li (0.39%) 8.9 8 90% E/6.2AA/28nBA200MI:10% E/5AA Na (1.98%) 1.2 990% E/6.2AA/28nBA200MI:10% E/5AA Na (1.58%) 2.0 10 90%E/6.2AA/28nBA200MI:10% E/5AA Na (1.41%) 4.0 11 90%E/6.2AA/28nBA200MI:10% E/5AA Mg (2.80%) 1.8 12 90%E/6.2AA/28nBA200MI:10% E/5AA Mg (1.94%) 3.1 13 90%E/6.2AA/28nBA200MI:10% E/5AA Mg (1.49%) 6.6

The soft and resilient bimodal ionomer compositions prepared as Examples1 through 13 were injection molded into flex bars for mechanicalproperty tests. After two weeks of annealing at ambient temperature(approximately 20 to 22° C.), the Shore D hardness at 10 seconds and theflex moduli were measured and are reported in Table 3. The soft andresilient bimodal ionomers were also injection molded into resin spheresand tested for golf ball properties after more than two weeks of agingat ambient temperature. The Atti compressions and the coefficients ofrestitution of the neat spheres are reported in Table 3.

TABLE 3 Injection-molded Testpiece Neat Sphere Properties Shore D FlexModulus Atti Example (10 sec.) (kpsi) Compression COR-125 1 35 4.69 520.629 2 34 3.97 40 0.595 3 31 3.59 27 0.573 4 40 6.14 71 0.682 5 38.55.29 67 0.677 6 36.5 5.45 72 0.669 7 30.3 4.00 49 0.636 8 34.5 4.60 730.678 9 34 3.77 67 0.673 10 30.5 3.72 56 0.660 11 38.8 7.01 60 0.677 1237.8 5.87 55 0.666 13 35 4.38 44 0.639

Preferred compositions are those exhibiting Shore D hardness of fromabout 30 to about 40 and flex moduli from about 3 to about 8 kpsi.

The soft and resilient bimodal ionomers of Examples 1 through 13 werealso injection molded as the cover layer over a commercial thermosetpolybutadiene golf ball core to prepare golf balls of this invention.The 2-piece golf balls were tested for scuff resistance after two weeksof aging at room temperature. The scuff ratings of the unpainted andotherwise unfinished 2-piece golf balls of this invention are given inTable 4. The commercial polyurethane (PU) covered golf balls, i.e.Titleist's ProV-1 and Nike's Accuracy (Comparative Examples 14 and 15respectively), were also tested for relative scuff resistance, and thetest results reported in Table 3 for comparison. The commercialComparative Examples are painted and/or fully finished for play. Theunpainted 2-piece balls of this invention, with covers prepared from thesoft and resilient bimodal ionomers described above demonstratedsuperior scuff resistance and improved resilience and soft feel, i.e.lower hardness and stiffness.

TABLE 4 Scuff Example Golf Ball with Cover Prepared from ExampleResistance Ionomer (Unfinished) 1 2-piece ball over polybutadiene core 12 2-piece ball over polybutadiene core 0.5 3 2-piece ball overpolybutadiene core 0.5 4 2-piece ball over polybutadiene core 1.5 52-piece ball over polybutadiene core 2 6 2-piece ball over polybutadienecore 2 7 2-piece ball over polybutadiene core 1 8 2-piece ball overpolybutadiene core 2.5 9 2-piece ball over polybutadiene core 2.75 102-piece ball over polybutadiene core 3 11 2-piece ball overpolybutadiene core 1.5 12 2-piece ball over polybutadiene core 1.5 132-piece ball over polybutadiene core 1 Commercial Standard Finished BallComp. 14 Commercial Titleist ProV-1 (TS PU cover) 3.5 Comp. 15Commercial Nike Accuracy (TP PU cover) 2.2

Testing Criteria for Examples

Melt Index (MI) was measured in accord with ASTM D-1238, condition E, at190° C., using a 2160-gram weight, with values of MI reported ingrams/10 minutes.

Shore D hardness was determined in accord with ASTM D-2240.

COR is measured by firing an injection-molded neat sphere of the resinhaving the size of a golf ball from an air cannon at a velocitydetermined by the air pressure. The sphere strikes a steel platepositioned three feet away from the point where initial velocity isdetermined, and rebounds through a speed-monitoring device located atthe same point as the initial velocity measurement. The return velocitydivided by the initial velocity is the COR. The initial velocitygenerally employed is 125 feet/second (COR-125).

Atti Compression (also known as PGA Compression) is defined as theresistance to deformation of a golf ball, measured using an AttiCompression Gauge. The Atti Compression Gauge is designed to measure theresistance to deformation or resistance to compression of golf ballsthat are 1.680 inches in diameter. In these examples, smaller spheres ofapproximately 1.53 inches in diameter were used. Spacers or shims wereused to compensate for this difference in diameter. The sphere diameterswere measured. A shim thickness was calculated such that the spherediameter plus shim thickness equaled 1.680 inches. Then the PGAcompression of the sphere and shim was measured. A set of shims ofdifferent thicknesses was used to correct the sphere diameter plus shimthickness to within 0.0025 inches of 1.680 inches. After the PGAcompression measurement was made, the value was mathematically correctedto compensate for any deviation from 1.680 inches. If the spherediameter plus shim thickness was less than 1.680 inches, one compressionunit was added for every 0.001 inch less than 1.680 inches. If thesphere diameter plus shim thickness was greater than 1.680 inches, onecompression unit was subtracted for every 0.001 inch greater than 1.680inches.

Scuff resistance was determined in the following manner: a D-2 toolsteel plate machined to simulate a sharp grooved pitching wedge withsquare grooves was obtained and was mounted on a swing arm that swingsin a horizontal plane. The simulated club face was oriented for a hit ona golf ball at a 54° angle. The machine was operated at a club headspeed of 140 feet per second. Balls were prepared as described abovefrom each of the test compositions. Comparison balls with polyurethanecovers were obtained commercially. At least three balls of eachcomposition were tested and each ball was hit once. After testing, theballs were rated according to the following criteria (see Table 5).Scuff damage was characterized by the presence of indented lines, liftsor groove bands. Indented lines are visible lines created by permanentdisplacement of the resin, but without cutting, breaking ordiscontinuity of the surface. Lifts are scuffs in which the resin isdisplaced enough that the surface is broken such that a portion of theresin is separated from the bulk of the ball. Severe lifts includeflaps, whiskers or strands. Groove bands are bands of resin missing fromthe bulk of the ball corresponding in dimension to a single groove ofthe club face. The ratings were assigned numerical values based on thecriteria in Table 5.

TABLE 5 0 No sign of impact 1 One or more indented lines on a ball, butno separation of resin from the bulk of the ball. 2 One or more lifts ona ball. Resin separated from the ball on one edge but still firmlyattached. 3 Severe lifts and whiskers. Flaps and strands of resinseparated from the bulk of the ball but generally still attached. 4 Oneor more groove bands, but undamaged resin between groove bands. 5Material missing entirely between two or more grooves bands.

Decimal fraction ratings can be assigned between these descriptions. Forexample, barely visible indented lines may be rated 1.0 while deeplyindented lines that push up ridges of the resin may be rated 1.8. Onelift may be rated 2.0 while three or four lifts may be rated 2.5. A ballrated 3 may look more damaged than a ball rated 4 or 5 because missingmaterial may be less noticeable than flaps and/or whiskers.

Golf balls of this invention have a scuff resistance less than or equalto 3.0 according to this rating system. More preferably, golf balls ofthis invention have a scuff resistance less than or equal to 2.5 andeven more preferably a scuff resistance less than or equal to 2.0.

1-32. (canceled)
 33. A composition comprising a bimodal compositionconsisting essentially of: (a) one or more E/X/Y terpolymers, wherein Erepresents copolymerized residues of ethylene, X representscopolymerized residues of a C3 to C8, α,β-ethylenically unsaturatedcarboxylic acid, and Y represents copolymerized residues of a softeningcomonomer selected from the group consisting of alkyl acrylates andalkyl methacrylates wherein the alkyl groups have from 1-8 carbon atoms,wherein the level of X is about 2 to 30 wt % and the level of Y is 0 toabout 35 wt % , based on the total weight of the E/X/Y copolymer, andwherein the molecular weight (Mw) of the E/X/Y copolymer is in the rangeof 80,000 to 500,000; and one or more E/X bipolymers, wherein Erepresents copolymerized residues of ethylene, X representscopolymerized residues of a C3 to C8, α,β-ethylenically unsaturatedcarboxylic acid, wherein the level of X is about 2 to 30 wt %, based onthe total weight of the E/X bipolymer, and wherein the molecular weight(Mw) of the E/X bipolymer is in the range of 80,000 to 500,000; (b) oneor more E/(M)AA copolymers comprising 3 to 25 wt % of copolymerizedresidues of (M)AA based on the total weight of the E/(M)AA copolymer,wherein the molecular weight (Mw) of the E/(M)AA copolymer is in therange of 2,000 and 30,000; and wherein the acid residues of (a) and of(b) are at least partially neutralized.
 34. The composition of claim 33,wherein the polydispersity (Mw/Mn) of each of the E/X/Y terpolymers andeach of the E/X bipolymers ranges from about 1 to about
 15. 35. Thecomposition of claim 34, wherein the polydispersity (Mw/Mn) of each ofthe E/X/Y terpolymers and each of the E/X bipolymers ranges from 5.1 to11.5.
 36. The composition of claim 33, wherein the one or more E/(M)AAcopolymers are present at a level of about 5 to about 50 wt %, based onthe total weight of (a) and (b).
 37. The composition of claim 33 whereinX represents copolymerized units of acrylic acid or methacrylic acid;and wherein Y represents copolymerized units of an alkyl acrylate. 38.The composition of claim 37 wherein the level of X in the E/X/Yterpolymer is 5 to 25 wt %.
 39. The composition of claim 37, wherein thelevel of X in the E/X/Y terpolymer is 8 to 20 wt %.
 40. The compositionof claim 37 wherein the level of Y in the E/X/Y terpolymer is 3 to 25 wt%.
 41. The composition of claim 37 wherein the level of Y in the E/X/Yterpolymer is 10 to 25 wt %.
 42. The composition of claim 37 wherein Yrepresents copolymerized residues of n-butyl acrylate.
 43. Thecomposition of claim 37 wherein X represents copolymerized residues ofacrylic acid.
 44. The composition of claim 37 wherein X representscopolymerized residues of methacrylic acid.
 45. The composition of claim33 wherein the level of X in the E/X bipolymer is 5 to 25 wt %.
 46. Thecomposition of claim 33 wherein the level of X in the E/X bipolymer is 4to 15 wt %.
 47. The composition of claim 33 wherein the level of X inthe E/X bipolymer is 4 to 11 wt %.
 48. The composition of claim 45wherein X represents copolymerized residues of methacrylic acid.
 49. Thecomposition of claim 33, wherein about 40 to about 100% of the acidresidues of (a) and of (b) are neutralized.
 50. The composition of claim33, wherein the acid residues of (a) and of (b) are at least partiallyneutralized to include zinc cations.
 51. The composition of claim 33,further comprising one or more optical brighteners, surfactants orprocessing aids.
 52. The composition of claim 33, further comprising upto 100 parts by weight of one or more organic acid salts, up to 200parts by weight of one or more thermoplastic elastomers, or up to 170parts by weight of one or more fillers, based on 100 parts by weight ofthe bimodal composition.
 53. A golf ball comprising the composition ofclaim
 33. 54. The golf ball of claim 48 wherein the composition is usedin the cover of the ball.
 55. An injection molded article, a film, aprotective coating, flooring or an article of footwear comprising thecomposition of claim 33.